Hammermill hammers

ABSTRACT

A hammermill hammer design to increase the life of the hammer due to the placement of more of the hard facing material on the working edge. The hammer has a steel body with end surfaces having a centrally raised portion on which surfaces hard facing material is applied to a depth at least equal to the height of the raised portion. The hammer corners are beveled to permit more facing material at the corners. Mounting pin holes are provided adjacent each end of the hammer such that it may be reversed when worn.

United States Patent Inventor Glenn D. Hedrick 905 Orchard Ave., St.Paul, Minn. 55103 Appl. No. 739,719 Filed June 25, 1968 Patented Feb. 9,1971 HAMMERMILL HAMMERS 5 Claims, 4 Drawing Figs.

U.S. Cl 241/197 Int. Cl B02c 13/28 FieldotSearch... 241/197, 300, 195;29/95 References Cited 7 I UNITED STATES PATENTS 2,237,510 4/1941Tankersley 241/195 2,763,439 9/1956 Mankoff 241/197 3,045,934 7/1962Eilers 241/197 FOREIGN PATENTS 685.821 1/1940 Germany .1 241/197 PrimaryExaminerDonald G. Kelly Artorney-John C. Barnes ABSTRACT: A hammermillhammer design to increase the life of the hammer due to the placement ofmore of the hard facing material on the working edge. The hammer has asteel body with end surfaces having a centrally raised portion on whichsurfaces hard facing material is applied to a depth at least equal tothe height of the raised portion. The hammer corners are beveled topermit more facing material at the corners. Mounting pin holes areprovided adjacent each end of the hammer such that it may be reversedwhen worn.

HAMMERMILL I-IAMMERS This invention relates to hammermill hammers havinga hard facing applied to an edge thereof in a manner to increase life ofthe hammers.

In a hammermill, large numbers of hammers are pivotally suspended aboutand along a rotating shaft on suitable arms by an opening near one endof the hammer. In use the hammers are subjected to severe abrasive andshock forces directed transversely of the hammers and longitudinally ofthe working end of the hammer. As the hammers wear where one leadingedge is no longer effective the hammers are turned to present adifferent corner in working position. For this reason the hammers aregenerally symmetrical to provide four working corners. After the hammersare turned to wear all four corners the hammers are replaced.

Hammermill hammers of this type are conventionally stamped from steelbar stock about one-eighth to one-half inch thick and l /to 3 incheswide. The hammer bodies, so formed, are then provided with a coating ofhard facing material at each end to increase the abrasion resistance ofthe working edges of the hammers.

The life of the hammer is dependent on amount or degree of hard facingon the hammer and how well the facing material is fused to the steelhammer body. US. Pat. No. 3,045,934, issued to H. F. Eilers, discloses acommercially available hammer with a hard facing. This hammer howeverhas no more than one-eighth to one-fourth inch of hard facing at thecorners, and wear of the working edge begins relatively soon afterplaced in operation.

The present invention provides a hammer with more hard facing materialat the corners and less material in the center of the body ends where itwill afford no worthwhile function. The hammer design of the presentinvention is also effective to resist spalling or breaking away of thehard facing when subjected to the transverse forces at the ends of thehammer.

The method of manufacturing the hammers according to the presentinvention comprises the steps of placing two rows of hammer bodies inabutting relationship in a fixture with the hammers in each row inface-to-face contiguous position, passing a hard facing applicatorlongitudinally of the rows above the inner half of each row to applymolten hard facing material to one-half of each hammer body in each row,allowing the material to cool, separating the rows by splitting the hardfacing material, transposing the rows and placing them in abuttingrelationship, passing a hard facing applicator longitudinally of therows above the inner half of each row to apply molten hard facingmaterial thereto, allowing the hard facing material to cool, separatingthe rows of hammers, and separating the individual hammers in each row.

The above and additional novel features and advantages of the presentinvention will be more apparent after reading the following descriptionwhich refers the accompanying drawing wherein:

FIG. 1 is an elevational view of a pair of hammers formed according tothe present invention as removed from a production fixture after onestep in the process;

FIG. 2 is a fragmentary perspective view of a fixture and hammerstherein diagrammatically illustrating one step in the method of makingthe hammers;

FIG. 3 is a fragmentary view of the hammer bodies placed in the fixtureprior to another step in the manufacture; and

FIG. 4 is a fragmentary perspective view of one end of a completedhammer.

Referring now to the drawing, FIG. 1 illustrates two hammer bodies 5 and6, each of identical shape as formed by stamping the same from a stripof steel bar stock having a width and thickness equal to that of eachhammer. Each hammer has an opening 8 adjacent each end, of a size andspaced to meet various hammermill requirements. The ends of the hammersare contoured to have a raised rib 9 at each end positionedsymmetrically along the longitudinal center line of the hammer and withflat or planar portions 10 leading to the corners which are preferablyrounded or beveled as illustrated at 11. The ribs 9 extend betweenone-sixteenth inch to onefourth inch above'the fiat portions 10 and arerounded to expose the entire end surface to the hard facing applicatorfor preheating and receiving molten hard facing material generallydesignated 12, whether cooled or molten. The operation and control ofthe applicator is such that a good thermal bond is formed between thehard facing material and the bar stock.

The end of the hammers of my invention will retain a maximum thicknessof the hard coating at the corners. The beveled corners place the hardfacing not only on the ends of the hammers and at the corners but downthe edge approximately one-eighth inch. This provides a longer hard wearsurface where the greatest forces which strike the end portionslongitudinally thereof are directed during use in the mills.

The hammers of the present invention are formed by placing two rows ofstamped hammer bodies in abutting parallel relationship with the hammersof each row placed in face-toface contiguous position in a fixture 15, aportion of which is shown in FIG. 2. This fixture 15 has a centralrectangular opening to receive about 8 dozen one-half inch thick hammerbodies. The bodies are clamped in the fixture and brought into a closefitting relationship. A hard facing applicator including a pair ofoxygen-acetylene flame heads is then moved down the middle of thefixture above one-half of each row of hammer bodies. A first head 17supplied with fuel through tube 18 and having a very high heat flamepreheats the inner one-half of the end surfaces of the hammers of eachrow to a temperature to wet those portions of the end surface of thehammer bodies. A second head 20, supplied with a gaseous fuel through atube 21, moves along the hammer bodies immediately behind head 17, andwith head 17 melts rods 22 of the hard facing material fed down betweenthe heads. The rods 22 are guided downward between the heads by suitablebrackets. The rods 22 supply the molten hard surfacing alloy or compound12, and when molten the material fills the cavity defined between theribs 9 of the two rows of hammers as shown in FIGS. 1 and 2. Afterallowing time for cooling the hard facing material, the two rows ofhammers are removed from the fixture 15 and the two rows of hammers areseparated. This can be accomplished by a sharp chisel blow along theabutting line at the opposite ends of the hammers. The rows are thentransposed and returned to the fixture 15 in a position as illustratedfrom one end in FIG. 3. Again the heads 17 and 20 are moved down themiddle of the rows, filling the center cavity with molten hard facingmaterial. When the material cools the hammers are removed from thefixture and the rows are separated at the center. Next, the individualhammers in each row are split apart by a chisel blow delivered betweenthe uncoated contacting faces of the hammers to separate the hammers andfracture the coating material along a plane coextensive with the hammerfaces.

When both ends of the bodies are to be hard coated the hammers are thenplaced in the same pattern as they were before being fractured intoindividual hammers with the fractured edges in mating position, and areinserted in the fixture 15 with the opposite uncoated ends upward orexposed and horizontally positioned. After movement of the heads 17 and20 of the hard facing applicator along the rows as then ex posed to fillthe cavity between the rows, the rows are again removed and split apart,as described above and transposed. Again the cavities are filled.Thereafter the hammers are removed, the rows split and individualhammers in each row separated affording finished hammers with each endhard faced as illustrated in FIG. 4.

The hard facing material may be any suitable material known in the artto provide a facing having a hardness high on the Rockwell scale.Examples of such materials are tungsten carbide, or iron alloysofchromium, molybdenum, cobalt and carbon.

The improved hammer of my invention provides a hammer with the hardfacing having a maximum depth at the corners and along the work engagingside to increase the life of the hammer. The method of forming thehammers in at least two rows in side-by-side relation permits the moltenmaterial to form the hard faced ends and not result in the loss of anysubstantial amount of material during the process.

I claim:

1. A hammermill hammer comprising a steel body comprising an end portionwith a longitudinal dimension greater than the width dimension, said endportion having generally planar surface portions separated by a raisedcentral portion, and hard facing material applied across said generallyplanar surface portions of the end portion to a depth thereon at leastequal to the height of said raised central portion.

2. A hammermill hammer as claimed in claim 1 wherein said end portionhas a width of between one-eighth to one-half inch and is straight inthe widthwise direction and in the longitudinal direction except forsaid raised central portion which joins a portion of said generallyplanar surface portions on each side by smooth contours, and wherein theend portion is beveled at the corners to shorten the edges of the bodyto permit more hard facing at the corners.

3. A hammermill hammer as claimed in claim 2 wherein the beveled cornersof said end portion extend down the edges of the bodies approximatelyone-eighth inch.

4. A hammermill hammer as claimed in claim 2 wherein the hammer issymmetrical at each end and the hard facing material on each end affordsa rectangular profile for the ends ofthe hammer. Y

5. A hammermill hammer having opposed planar faces and generally similarend portions. said end portions each comprising planar surface portionsseparated by a smoothly contoured central rib portion extending in awidthwise direction across said end portion 'between said planar faces,and hard facing material joined to said end portions by a thermal bondsaid hard facing material having a depth on said planar surface portionsat least equal to the height of said rib portion defining on said hammeras a uniform hard wear resistant coating along said planar surfaceportions to said central rib portion.

1. A hammermill hammer comprising a steel body comprising an end portionwith a longitudinal dimension greater than the width dimension, said endportion having generally planar surface portions separated by a raisedcentral portion, and hard facing material applied across said generallyplanar surface portions of the end portion to a depth thereon at leastequal to the height of said raised central portion.
 2. A hammermillhammer as claimed in claim 1 wherein said end portion has a width ofbetween one-eighth to one-half inch and is straight in the widthwisedirection and in the longitudinal direction except for said raisedcentral portion which joins a portion of said generally planar surfaceportions on each side by smooth contours, and wherein the end portion isbeveled at the corners to shorten the edges of the body to permit morehard facing at the corners.
 3. A hammermill hammer as claimed in claim 2wherein the beveled corners of said end portion extend down the edges ofthe bodies approximately one-eighth inch.
 4. A hammermill hammer asclaimed in claim 2 wherein the hammer is symmetrical at each end and thehard facing material on each end affords a rectangular profile for theends of the hammer.
 5. A hammermill hammer having opposed planar facesand generally similar end portions, said end portions each comprisingplanar surface portions separated by a smoothly contoured central ribportion extending in a widthwise direction across said end portionbetween said planar faces, and hard facing material joined to said endportions by a thermal bond, said hard facing material having a depth onsaid planar surface portions at least equal to the height of said ribportion defining on said hammer as a uniform hard wear resistant coatingalong said planar surface portions to said central rib portion.